Although somewhat in a decline in recent years, auto theft is a continual problem. Nationwide in the U.S. in 2005, there were an estimated 1.2 million motor vehicle thefts, or approximately 416.7 motor vehicles stolen for every 100,000 inhabitants. Property losses due to motor vehicle theft in 2005 were estimated at $7.6 billion. Since then the number of motor thefts nationally has declined. The most recent statistics, for 2009, show an estimated 794,616 thefts of motor vehicles nationwide, representing property losses of nearly $5.2 billion.
Today, many motor vehicles utilize immobilizer systems where a master module seeks confirmation of the presence of other modules, such as a key fob, before allowing a vehicle to start. This master module has typically been the engine control module (ECM).
FIG. 1 is a simplified functional block diagram of a prior art theft deterrent system 10 for a vehicle 1. The system comprises a key/key fob with an electronic transponder 2. The vehicle 1 comprises an immobilizer module 5 and an engine control module 3 with a secret key code 4 that may be a random number, which is shared (i.e., known) by the immobilizer module 5 and the transponder 2. When the immobilizer module 5 detects the transponder 2, the immobilizer module 5 transmits a challenge signal 6 to the transponder 2. The transponder replies with a response computed using with the secret key code 4. When the immobilizer module 5 receives the response which correctly matches its expected response value, it communicates with the ECM 5 to allow the engine to start.
The communication between the immobilizer module 5 and the ECM 3 may occur through unsecured data transmission, password protected data transmission, or an additional challenge/response mechanism using the same or different secret key code 4 used by the immobilizer module 5 and transponder 2.
The relationship between the challenge 6 and the response 7 between the immobilizer module 5 and the transponder 2 is based on a cryptographic algorithm that utilizes the secret key code 4 shared by the immobilizer module 5 and the transponder 2. Those skilled in the art know that there are several methods by which this may be done—examples include the transponder computing a cryptographic Message Authentication Code (MAC) on the challenge (possibly along with other fixed form information) utilizing the secret key code 4, or encrypting the challenge 6 (possibly along with other fixed-form information) using a block cipher.
Examples of Message Authentication Code algorithms include HMAC (standardized in Federal Information Processing Standard Publication 198) and CMAC (standardized in NIST Special Publication 800-38); Examples of block ciphers include the Advanced Encryption Standard (AES) standardized in Federal Information Processing Standard Publication 197 and the Data Encryption Standard (DES), standardized in Federal Information Processing Standard Publication 46-3. In the case of a MAC-based approach the immobilizer module 5 would perform the same operation and verify that the challenge 6 provided by the transponder 2 is correct.
In the encryption-based approach the immobilizer module 5 would decrypt the challenge 6 and verify that the decryption has the expected form, or perform an identical encryption and verify that the challenge 6 matches the expected value. Regardless of the particular method used, the process of both generating the response 7 (done by the transponder) and verifying that the response 7 is correct (done by the immobilizer module 5) requires knowledge of the secret key code.
While this methodology is effective at a certain level, the situation where only one master immobilizer module 5 provides the final authorization necessary to start the vehicle may not always provide for an optimal theft deterrent system, for example due to possible tampering with the immobilizer unit 5 or ECM 3 by a hacker in order to start the vehicle. Physical part swapping and software manipulation remain problems to be resolved.
Thus, it is desirable to address these issues and provide improved theft deterrence by enhancing the theft deterrent systems in vehicles. Furthermore, other desirable features and characteristics of the systems and methods disclosed herein will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the preceding background.